What is Booting in Operating System?

Booting in Operating System

"Booting" might sound like a peculiar term if you're new to computing, but it's a foundational process that takes place every time you switch on your computer. The simple question "what is booting?" can be explained as the process by which a computer starts up, initializing its hardware components and launching its operating system (OS) from the computer's storage into its working memory.

What happens in the Process of Booting?

Let's understand

• What happens when the computer switch is pressed?
• How does our computer get started?
• What all things go in the backend so that our computer is ready to run the application programs?

We have been using computers for a long time but have never thought about what steps our computer system goes through.

let’s learn this all-new concept of what is booting, the booting process, types of booting, etc. by the end of this article.

Whenever we press the power button of our computer system, all the devices get the power and they are initialized. Our main memory which is responsible for holding the instructions will be initially empty as RAM is volatile memory. So, there will be a small set of instructions present in the non-volatile memory called ROM. These instructions will be passed to the CPU and the execution of instructions takes place which will check all the hardware connected with the system. If there are any problems with the hardware, we will get the alert by beep sounds or even on-screen messages. After the testing of the hardware is completed, the booting process continues and loads the operating system. The instructions present in non-volatile memory are hardwired on the motherboard so they can’t be erased.

The small set of instructions present in the ROM is called BIOS which stands for Basic Input Output System.

Let’s look into the details, of the steps involved in the booting process of the operating system now.

Types of Booting

There are two types of Booting available:

1. Cold Booting/ Hard Booting: Cold booting is the process when our computer system moves from the shutdown state to the start by pressing the power button. The system reads the BIOS from ROM and will eventually load the Operating System.

2. Warm Booting/ Soft Booting: Warm booting is the process in which the computer gets restarted due to reasons like setting the configuration for newly installed software or hardware. Warm booting is called as rebooting.

When our system gets hung and we restart the device, we are doing the Warm booting.

Let’s see how the system boots in detail.

Steps In the Booting Process

When the computer is powered on, all the hardware components receive the power and they get initialized. After that, the computer system goes through 6 steps booting process as follows:

1. Loading of BIOS: The small set of instructions present in the ROM is loaded into the computer memory and the CPU executes those instructions.

2. Power-On Self Test (POST): In order to check the operability of all the hardware connected to our computer system, BIOS carries out POST which will check the hardware components and if any problem is found user is alerted with POST beeps and POST screen messaged.

3. Loading of Operating System:

   • After the successful completion of POST, the bootable sequence present in CMOS (Common Metal Oxide Semiconductor) is read by BIOS.
   • Based on the bootable sequence it will search for Master Boot Record (MBR) in bootable devices like floppy disk, CD-ROM, and hard disk.
   • If MBR is not found in any of them, the system will halt by displaying “No Boot Device Found”.
   • if MBR is found, the BIOS will load the special application program called Boot Loader, which will eventually load the Operating system.

4. System Configuration is Accomplished: After the OS is loaded, device drivers are loaded into the memory so that our devices can function correctly.

5. System Utilities are Loaded: System utilities like antivirus, volume control, etc. are loaded into the memory in this step

6. User Authentication: If any user authentication is being set, the system will ask the user to enter the credentials, and on receiving the correct credentials the computer system will run GUI shell (in most cases) or CLI shell.

As BIOS is lightweight, it will just load the Boot Loader which can load the Complex set of libraries required for loading the Operating System. BIOS can’t directly load the heavily weighted set of instructions responsible for loading the Operating System.

Now let’s learn the type of booting.

What is Dual Booting?

When we have two different operating systems on our computer it is called Dual Booting. But now as we have multiple OS present, the bootloader needs to load the Operating System which the user selects from the menu that is being displayed on the monitor. If no action is performed within a few seconds, the default Operating System is loaded.

We can have multiple Operating Systems on the single bootable device by Creating Partitions.

By creating a partition on the bootable device like a hard disk, each partition can have its own Operating System and during run time on selection of the Operating System from the user, that particular Operating System is loaded into the memory of the computer system.